The Applicant has developed a wide range of printers that employ pagewidth printheads instead of traditional reciprocating printhead designs. Pagewidth designs increase print speeds as the printhead does not traverse back and forth across the page to deposit a line of an image. The pagewidth printhead simply deposits the ink on the media as it moves past at high speeds. Such printheads have made it possible to perform full colour 1600 dpi printing at speeds in the vicinity of 60 pages per minute, speeds previously unattainable with conventional inkjet printers.
Printing at these speeds consumes ink quickly and this gives rise to problems with supplying the printhead with enough ink. Not only are the flow rates higher but distributing the ink along the entire length of a pagewidth printhead is more complex than feeding ink to a relatively small reciprocating printhead.
Air bubbles can be introduced into the ink flow by outgassing or during the reconnection of the ink coupling to the printhead. Air bubbles trapped against the dirty side of the filter can prevent ink flow through that part of the filter. While ink will still flow through the wet areas of the filter, but the flow rate is reduced because of the reduced wetted surface area. The filter surface area can be over specified to accommodate some loss to bubbles. However, a large filter necessarily occupies more space and is detrimental to compact design.